Reduction in the cellular levels of the cyclin kinase inhibitor p27kip1 is frequently found in many human cancers and correlate directly with patient prognosis (Philipp-Staheli, J., Payne, S. R. and Kemp, C. J. p27(Kip1): regulation and function of a haplo-insufficient tumour suppressor and its misregulation in cancer. Exp Cell Res 264, 148-68 (2001)). Specifically ubiquitin dependent proteasomal turnover has been shown to cause reduced p27 expression in many human cancers (Loda, M. et al. Increased proteasome-dependent degradation of the cyclin dependent kinase inhibitor p27 in aggressive colorectal carcinomas. Nat Med 3, 231-4 (1997)).
GB 2,367,553 discloses pharmaceutically active macrocycles (“argyrines”) and respective pharmaceutical preparations for the treatment of autoimmune diseases, the induction of immunotolerance or the treatment of bacterial infections.
Sasse F et al. (in Sasse F, Steinmetz H, Schupp T, Petersen F, Memmert K, Hofmann H, Heusser C, Brinkmann V, von Matt P, Hofle G, Reichenbach H. Argyrins, immunosuppressive cyclic peptides from myxobacteria. I. Production, isolation, physico-chemical and biological properties. J Antibiot (Tokyo). 2002 June; 55 (6):543-51.) describe the production of a group of cyclic peptides called argyrins, as well as some of their biological properties. Vollbrecht et al. (in Vollbrecht L, Steinmetz H, Hofle G, Oberer, L, Rihs G, Bovermann G, and von Matt P. Argyrins, immunosuppressive cyclic peptides from myxobacteria. II. Structure elucidation and stereochemistry. J Antibiot (Tokyo). 2002 August; 55 (8):715-721.) describe the structure of said cyclic peptides. Argyrines A-H can be obtained from the myxobacterium Aarchangium gephyra. 
Similarly, Ley et al. (in Ley SV, Priour A, Heusser C. Total synthesis of the cyclic heptapeptide Argyrin B: a new potent inhibitor of T-cell independent antibody formation. Org Lett. 2002 Mar. 7; 4 (5):711-4.) describe the synthesis of argyrin B and its function as inhibitor of antibody formation.
EP1964560 describes the use of the macrocycles of GB 2,367,553 for the production of a medicament for the treatment of cancer in a subject.
WO/2010/006682 “Method for producing intermediates for the production of novel macrocycles that are inhibitors of the proteasomic degradation of p27, such as argyrin and derivatives thereof, and uses of said macrocycles”, which is herewith incorporated by reference in its entirety, describes intermediates for the production of macrocycles that are inhibitors of the proteasomic degradation of p27, such as argyrin and derivatives thereof, as well as methods for the production and biological activity of said macrocycles.
Argyrines and related macrocycles are therefore interesting candidates for the further development of medicaments for a treatment in a variety of conditions, such as the induction of immunotolerance, autoimmune diseases, bacterial infections, and proliferative diseases, such as cancers.
Nevertheless, the full exploitation of the pharmaceutical potential of argyrines and their related derivatives is difficult because of their relatively complex chemical structure, which requires laborious efforts to isolate sufficient amounts of the compounds (e.g. from micro-organisms), and limits the number of effective compounds of this family that are readily available for studies and treatment. It is particularly difficult to readily produce stereoselective forms of argyrines in a sufficient amounts and purities.
It is therefore an object of the present invention to provide improved methods for the production of compounds of the family of argyrines, and respective intermediates.
According to a first aspect of the present invention, the above object is solved by a method for producing optionally protected L-4-methoxytryptophane comprising the synthesis of the protected L-4-methoxytryptophanemethylester according to formula 2
comprising an asymmetric hydrogenation using [1S,1S′,2R,2R′-DuanPhos Rh(cod)]BF4 as a catalyst. According to a second aspect of the present invention, the above object is further solved by a method for producing optionally protected D-4-methoxytryptophane comprising the synthesis of the protected D-4-methoxytryptophanemethylester according to the formula
comprising an asymmetric hydrogenation using [1R,1R′,2S,2S′-DuanPhos Rh(cod)]BF4 as a catalyst.
Thus, preferred is a method for producing stereoselective optionally protected D-4- or L-4-methoxytryptophane using catalytic asymmetric hydrogenation, wherein the catalyst is prepared from [Rh(cod)2]BF4 and 1S,1S′,2R,2R′-DuanPhos or 1R,1R′,2S,2S′-DuanPhos respectively. Preferred is a method, wherein the enantiomeric excess is at least 97% ee, and 98% ee, respectively. Most preferred is more than 99% ee.
Initially, 4-methoxy-L-tryptophane could only be produced through an enzymatic resolution (Ley, S. V.; Priour, A. Eur. J. Org. Chem. 2002, 3995-4004; Ley, S. V.; Priour, A.; Heusser, C. Org. Lett. 2002, 4, 711-714). The yields that can be obtained in principal can never exceed 50%. In practice, only yields of as low as between 10 and 40% were reached. PCT/EP2009/004526 describes a synthesis that can only be achieved with a selectivity of 90% ee. It was now surprisingly found that, using the hydrogenation catalysts as presented herein, a markedly improvement could be achieved in the asymmetric hydration and therefore both in the synthesis of the methoxytryptophane element and the overall synthesis of argyrines.
Thus, further preferred is a method for producing a macrocycle compound according to the present invention or 4-methoxy-L- or 4-methoxy-D-tryptophane as above, wherein the synthesis is performed without the uses of enzymes.
Even further preferred is a method for producing a macrocycle compound according to the present invention, wherein said synthesis comprises a solid phase synthesis. More preferably, said synthesis comprises solid phase peptide synthesis of a linear precursor involving the above mentioned amino acid. The solid phase synthesis allows elimination to produce the exo-methylen group after ring closure.
In the method for producing a macrocycle compound according to the present invention said asymmetric hydrogenation can be carried out under a pressure of between 1 and 100 bar, preferably between 1 and 20 bar, and most preferably 1 to 10 bar. Preferred is a method for producing a macrocycle compound according to the present invention, wherein said asymmetric hydrogenation is carried out at a temperature of between 15° C. and 100° C. Also preferred is a method for producing a macrocycle compound according to the present invention, wherein said asymmetric hydrogenation is carried out using alcohol, and preferably methanol, as a solvent. Advantageously, the present method provides the tryptophane element(s) with a very high specific ee-value. This simplifies the purification at the end of the synthesis and increases the yield(s).
According to a third aspect of the present invention, the above object is solved by a method for producing a macrocycle compound according to the following general formula (I)
wherein R1 and R2 independently are hydrogen, C1-C4 alkyl which is unsubstituted or substituted by OH, or C1-C4 alkoxy; R3 is hydrogen, C1-C4 alkoxy, C1-C8 alkyl which is unsubstituted or substituted by OH or OR, wherein R is selected from hydrogen, C1-C4 alkyl, aryl or acetyl, or C1-C4 alkoxy, R4 is hydrogen, halogen, C1-C4 alkyl which is unsubstituted or substituted by OH, or C1-C4 alkoxy; R5 is hydrogen or halogen; R6 is hydrogen or C1-C4 alkyl; R7 is hydrogen or C1-C4 alkyl which is unsubstituted or substituted by OH, or C1-C4 alkoxy; and X is C═CH2 or CHR8 wherein R8 is C1-C4 alkyl which is unsubstituted or substituted by —S—C1-C4 alkyl, and stereoisomers and pharmaceutically acceptable salts thereof, comprising a synthesis of optionally protected 4-methoxy-tryptophane according to the present invention. Preferred is a method as above, wherein R7 is hydrogen or C1-C4 alkyl which is unsubstituted or substituted by OH, or C1-C4 alkoxy; and X is C═CH2 or CHR' wherein R7 is C1-C4 alkyl which is unsubstituted or substituted by —S—C1-C4 alkyl. More preferred is a method as above, wherein if R1 is not hydrogen, X must be CH2.
Further preferred is a method for producing a macrocycle compound according to the present invention, wherein said macrocycle compound is selected from an argyrin, such as argyrin A-F, B/F, and Ala alpha and Ala beta, and isolated stereoisomers thereof. Particularly preferred is a method of the present invention as above for producing a macrocycle compound that is selected from the following formulae
and pharmaceutically acceptable salts thereof.
Further preferred is a method for producing a macrocycle compound according to the present invention further comprising the step of a chemical modification of said compound. In this case, the compound will function as a so-called “lead-structure” which is further subjected to chemical modifications which are then screened for their effectiveness to increase the amount and/or biological activity of p27 in one or more subsequent screening methods as known. Modification can be effected by a variety of methods known in the art, which include, without limitation, the introduction of novel side chains or the exchange of functional groups like, for example, introduction of halogens, in particular F, Cl or Br, the introduction of lower alkyl groups, preferably having one to five carbon atoms like, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl or iso-pentyl groups, lower alkenyl groups, preferably having two to five carbon atoms, lower alkynyl groups, preferably having two to five carbon atoms or through the introduction of, for example, a group selected from the group consisting of NH2, NO2, OH, SH, NH, CN, aryl, heteroaryl, COH or COOH group. Furthermore, additional peptide groups could be added to the molecule, such as single amino acids, dipeptides, tripeptides, and so on.
Yet another aspect of the present invention is directed to a method for producing a pharmaceutical composition, comprising the method for producing a macrocycle compound according to the present invention as herein, and admixing said macrocycle compound together with pharmaceutically acceptable carriers and/or excipients. Carriers, excipients and strategies to formulate a pharmaceutical composition, for example to be administered systemically or topically, by any conventional route, in particular enterally, e.g. orally, e.g. in the form of tablets or capsules, parenterally, e.g. in the form of injectable solutions or suspensions, topically, e.g. in the form of lotions, gels, ointments or creams, or in nasal or a suppository form are well known to the person of skill and described in the respective literature.
Administration of an agent, e.g., a compound can be accomplished by any method which allows the agent to reach the target cells. These methods include, e.g., injection, deposition, implantation, suppositories, oral ingestion, inhalation, topical administration, or any other method of administration where access to the target cells by the agent is obtained. Injections can be, e.g., intravenous, intradermal, subcutaneous, intramuscular or intraperitoneal. Implantation includes inserting implantable drug delivery systems, e.g., microspheres, hydrogels, polymeric reservoirs, cholesterol matrices, polymeric systems, e.g., matrix erosion and/or diffusion systems and non-polymeric systems, e.g., compressed, fused or partially fused pellets. Suppositories include glycerin suppositories. Oral ingestion doses can be enterically coated. Inhalation includes administering the agent with an aerosol in an inhalator, either alone or attached to a carrier that can be absorbed. The agent can be suspended in liquid, e.g., in dissolved or colloidal form. The liquid can be a solvent, partial solvent or non-solvent. In many cases, water or an organic liquid can be used.
Yet another aspect of the present invention is then directed to a pharmaceutical composition that is produced according to the method as above.
Another aspect of the present invention is the use of a pharmaceutical composition produced according to the present invention for the treatment of a disease or condition selected from the induction of immunotolerance, autoimmune diseases, bacterial infections, and proliferative diseases, such as psoriasis or cancers, such as breast cancer, hepatocellular carcinoma, myeloma, cervix carcinoma, lung carcinoma, and colon cancer. Yet another aspect of the present invention is the use of a compound according to the present invention for the production of a medicament for the treatment of a disease or condition selected from the induction of immunotolerance, autoimmune diseases, bacterial infections, and proliferative diseases, such as psoriasis or cancers, such as breast cancer, hepatocellular carcinoma, myeloma, cervix carcinoma, lung carcinoma, and colon cancer.
The biological effects of different argyrin-derivatives as synthesized was tested as described in the examples section of WO/2010/006682 (herewith incorporated by reference), and were found to be essentially identical. Thus, compounds as produced according to the present method are effective in the treatment of a disease or condition selected from the induction of immunotolerance, autoimmune diseases, bacterial infections, and proliferative diseases, such as psoriasis or cancers, such as breast cancer, hepatocellular carcinoma, myeloma, cervix carcinoma, lung carcinoma, and colon cancer.
It is assumed that the possibility to synthesize the active compounds in better yields and purities will also improve the effect of respective pharmaceutical compositions, as lower dosages can be used leading to fewer potential side effects. Furthermore, a more straight forward synthesis improves the safety of a respectively produced medicament, as, for example, fewer mistakes can be made in the production process.
The following examples merely serve to illustrate the invention and should not be construed to restrict the scope of the invention to the particular embodiments of the invention described in the examples. For the purposes of the present invention, all references as cited herein are hereby incorporated herein by reference in their entireties. It should be understood that the following syntheses can be readily modified by the person of skill in order to synthesize other derivatives of the present invention based on the strategies as provided.